Microbiota-Directed Therapies for the Treatment of Small Intestinal Bacterial Overgrowth: A Systematic Review and Meta-Analysis

Vollständiger Abstract

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Small intestinal bacterial overgrowth (SIBO) is characterized by an excessive proliferation of bacteria within the small intestine, resulting in chronic gastrointestinal symptoms, impaired quality of life, and frequent recurrence. Although rifaximin remains the cornerstone of treatment, increasing interest has focused on microbiota-directed therapeutic strategies aimed at restoring intestinal homeostasis and addressing mechanisms beyond bacterial eradication. This systematic review and meta-analysis evaluated the efficacy, safety, and clinical relevance of microbiota-directed interventions compared with conventional antibiotic therapy, placebo, or no intervention in adults with breath test-confirmed SIBO. A systematic search identified nine eligible studies involving 782 participants. Methodological quality was assessed using the CASP and PEDro tools, while risk of bias was evaluated using the Cochrane Risk of Bias 2 (RoB 2) tool and ROBINS-I. A random-effects meta-analysis was performed whenever clinically comparable studies reporting extractable dichotomous data were available. The primary meta-analysis demonstrated that adjunctive microbiota-directed therapies combined with antibiotics significantly improved breath test-confirmed SIBO eradication compared with antibiotic monotherapy (RR 1.36, 95% CI 1.13–1.65; I2 = 0%). An exploratory meta-analysis including all eligible interventions yielded consistent findings (RR 1.34, 95% CI 1.14–1.57; I2 = 1.1%). The qualitative synthesis identified symptomatic improvements in some individual studies; however, these findings were heterogeneous across symptom domains, assessment methods, and underlying clinical populations. Evidence regarding health-related quality of life and selected microbiota-related and inflammatory biomarkers was also limited, whereas adverse events were generally mild and infrequent. Overall, the available evidence suggests that microbiota-directed therapies, particularly when used as adjuncts to antibiotic treatment, may represent a promising complementary approach for improving SIBO eradication without compromising safety. However, the certainty of the available evidence remains limited by the small number of studies, heterogeneous interventions, and variability in outcome reporting. Larger, well-designed randomized controlled trials are warranted to confirm these findings and define the optimal microbiota-directed therapeutic strategy.